This invention relates to a solid state imaging device particularly used for an imaging unit for a video camera.
A solid state imaging device generally comprises a photodiode array and a transfer section such as a charge coupled device (CCD) for transferring signal charges generated in the photodiode array. The transfer section such as a CCD includes an impurity diffusion region constituting a transfer channel formed in a substrate and a control electrode which is made of light transmissible thin film and disposed above the transfer electrode through an insulation film. An aluminium film as a light shield means is formed on the control electrode through an insulation film.
With the solid state imaging device of the type described above, in order to attain a high speed operation, it is necessary to lower the resistance of the control electrode by making electric contact between the control electrode and the aluminium film. For this purpose, a contact hole is formed in the insulation film interposed between the aluminium film and the control electrode. However, since the insulation film interposed between the control electrode and the transfer electrode is very thin and control of the etching depth is difficult, the contact hole may reach the transfer electrode. This results in a short circuit, which will lower the yield of the products. On the other hand, in order to obviate the lowering of the yield, it is unavoidably necessary to operate the imaging device with inadequate characteristics or performance.